Fire and explosion are often synergistic. A fire may occur after an explosion or a fire may occur first and then an explosion occurs. The consequences of a combined fire and explosion scenario about each component must be considered in the design or evaluation of the structure. The analysis of fire and explosion should be done together and the effects of one on the other should be carefully analyzed. In most researches and design guidelines, fire and explosion phenomena are investigated independently and their interaction is less considered. In this research, this issue is addressed and the fire after the explosion and the interaction and synergy of these two phenomena are studied together. The studied structure is a two-story Steel structure with different occupancy (dwelling, office, etc.). which is subject to various explosions and as a result fire caused by the equipment inside the building. Explosive loading has been calculated using UFC 3-340-02 instruction charts and fire load using the concept of fire density and relationships of EUROCODE 1 and EUROCODE 3 regulations. In order to simulate explosive and thermal loading, Abaqus finite element software and combined thermal-deformation dynamic analysis have been used. The temperature caused by the fire has been used as a natural fire, and the cooling and post-cooling stages of the fire have also been investigated. After validating the proposed simulation with two valid laboratory works, the analysis of the structure's response against various types of explosive loads and subsequent fires was performed by a numerical model. The results of these investigations showed that the response and deformation of the structure in the chain combined analysis (applying the interaction of explosion and fire on the structure) compared to the independent combined analysis (independent analysis of the structure against explosion and fire and collecting the responses together) It increases by 15%, and considering the interaction of explosion and fire is not only important but also necessary, and not considering this interaction in most cases will cause the response of the structure to be less than the reality, and as a result, it will cause an unsafe design.

In this study, the pre-approved connection and the proposed connection have been investigated and analyzed using Abaqus finite element software. Non-linear static analysis was performed with reciprocating loading. In this study, in order to compare the proposed connection and the direct connection, two one-story and six-story Frames has been modeled and the behavior of the two connections in these Frames has been investigated. According to the software models, it can be seen that in all the models, the Bending moment capacity of the connection is more than 40% of the calculated plastic moment in the connection. In connection with the reduced cross-section, this percentage has reached nearly 20%. The results of the proposed connection behavior show that it performs nearly 25-34% better than the pre-validated connection of the 10th topic of Iran regulation of structures. The structure with the proposed connection has a higher coefficient of behavior than direct connection. With the increase in the height of the structure, the coefficient of behavior of the structure has also decreased.

A separated plastic strength surface is used for second order plastic analysis of Frames under week-axis Bending effect of columns. This surface considers the interaction of axial force and Bending in reduction of member stiffness. Also, two functions for reducing the stiffness are suggested. In order to show the ability of these functions, a variety of Frames with weak-axis Bending of columns are analyzed. These have been done by authors computer program. The results demonstrated that this plastic strength surface gives little error for week-axis Bending effect.

One of the most important issues in passive defense considerations is progressive collapse. For instant destruction of Structural member due to different incidents such as deliberate or unexpected events, propagation of destruction to adjacent members and inability of building to achieve static alternative equilibrium conditions, progressive collapse occurs, which leads to partial or even total destruction. On the other hand, removing critical members in different buildings situations may have various progressive collapse potentials. Catenary action is a building rehabilitation mechanisms to achieve equilibrium alternative and stability of the structure. In this study, based on the sixth and tenth national building regulations and using vertical push nonlinear static analysis (Push-Down Analysis) and nonlinear dynamic time history analysis of Steel Bending Frame structures, performance of the structure by removing columns in different locations and its effect on potential progressive collapse, are discussed. The results show that it has highest effect when a corner column is removed while it has lowest catenary action in building. Structural stability to achieve alternative equilibrium after columns removal, will improve by strengthening catenary action building performance.

The analysis and design of structures based solely on the elastic behavior of the members and the lack of attention to the plastic behavior in tolerating of the lateral forces leads to noneconomic design. All the regulations in the world, a special coefficient, called the building's coefficient of behavior, which is calculated to reduce the earthquake forces is considered and allows the designer to analyze the elastic structure under reduced forces and design based on its results. The magnitude of this coefficient in the earthquake regulations is based primarily on the observations of the performance of various building Systems in past strong earthquakes and based on engineering judgments. Accordingly, many researchers have expressed concern about the lack of reasonable coefficient of behavior, based on research studies and computational backing in earthquake regulations, and emphasized on the correction of these coefficients based on scientific studies. By studying the results of dynamic analysis on the studied structures in two types with behavior factor 6 and behavior 7, it was shown that increasing the coefficient of behavior can play a very important role in the Seismic response. The coefficient of behavior in the building does not have a significant effect on the horizontal displacement of the structure. Because in the buildings of one and four story, according to the 2800, the effect of twisting is not considered, and because of this, the coefficient of behavior in the buildings of one and four floors does not have much effect on the earthquake force.

In this paper, to increase the ductility in Steel concentrically braced Frames, a new quadrilateral Bending fuse is suggested at the intersection of the braces. In the first part, in order to achieve suitable dimensions, a diverse range of fuse dimensions and the behavior of the built models have been evaluated using ABAQUS software. The obtained results indicate that the maximum base shear and stiffness of the structure decreases with the increase in the dimensions of the opening used. The ratio of lateral stiffness value for 3% opening compared to X bracing is 44%, for 5% opening compared to X bracing it is 44% and for 10% opening compared to X bracing it is 20%. In the second part of the studies, firstly, a two-dimensional Frame was designed using Steel concentrically braced Frames in ETABS software, and then three fifteen floors two-dimensional Frame models by replacing quadrilateral Bending fuses with 3, 5, and 10% opening percentages in OpenSees software was investigated. To evaluate the performance of studied Frames, nonlinear dynamic time history analysis and nonlinear static analysis performed using different near field and far field accelerations was investigated. The meaning of 3% opening percentage is that the area of the quadrilateral fuse installed in the middle of the cross brace is equal to 3% of the product of the opening length of Frame in the height of the floor. The results of dynamic analysis of time history show that for the near field earthquakes, the average base shear ratio for openings of 3%, 5% and 10% compared to X bracing is 72%, 40% and 26%, respectively. These values are equal to 72%, 38% and 24% for the far field, respectively.

The purpose of the current research was to investigate the obstacles to the implementation of school-based management in Iran's educational System based on the interpretive Structural modeling approach. The research method was a modeling study. The statistical population of the research was specifically the academic staff members of the university, 25 of whom were purposefully selected from the desired cases. The data collection tool was a researcher-made self-interactive questionnaire. In order to measure and evaluate the validity of the questionnaire, the criterion of content validity was used. The content validity of the questionnaire was 0.96. The data analysis was done with interpretive Structural modeling method. The results of the research showed that 9 factors play a role as barriers to school-oriented management. Also, the results showed that financial obstacles (the cost of school-oriented management), socio-cultural obstacles and political obstacles (political focus on schools by the central government) as key independent variables have high influence power and low dependence. Also, the results showed that the lack of belief in the professional competence of school administrators, the lack of infrastructure facilities, the emphasis of upper management on the supervision and control of schools, and the lack of cooperation of local communities with school-based management as the linking variables with the greatest power of influence and the greatest power of dependence. and the centralism in the education System of the country and the lack of legal powers to school managers and staff as dependent variables have high dependency power and low influence power.

In performance-based engineering, conservatism in acceptance criteria at Structural performance levels has increased the cost of retro tting. In seismic rehabilitation of structures, uncertainties associated with existing structures have been studied and rehabilitation guidelines have been applied to deal with these uncertainties in terms of reliability index. The secondary System, which is added to the existing structure, is subject to uncertainties in seismic rehabilitation of structures. These uncertainties can escalate the uncertainties of rehabilitated structures and may change the analysis results such as reliability index parameter, values of fragility, and inter-story drift. Therefore, this study investigated the reliability of the structure rehabilitated with Steel shear wall and performed a parametric study on the reliability index. The selected structure was a Steel moment Frame, which was rehabilitated by the Steel shear wall. The structure was subject to incremental dynamic analysis before and after rehabilitation with probabilistic variables. Based on the results, the values of the reliability index were obtained for the rehabilitated structure in the presence of uncertainties. According to results, Structural rehabilitation reduced failure probability and consideration of uncertainties in the rehabilitated structure increased the probability of failure. Therefore, existing conservatism was reduced.

Uncertainties are inevitable in the estimation of Structural engineering issues and increase the cost of retrofitting. In the presence of uncertainties, the results of seismic evaluation are incorrect and create conservatism in acceptance criteria at Structural performance levels. Considering and quantification of uncertainties in design and rehabilitation of structures reduces the existing conservatism and can lead to the economic design and rehabilitation of structures. In the seismic rehabilitation of structures, uncertainties have been studied on existing structures and have been applied by coefficients in guidelines. Adding a secondary System to rehabilitate of existing structure can enter uncertainties into the computation and can be effective for results of reliability. Therefore, in this study, reliability of rehabilitated Steel moment Frame with Steel shear wall has been discussed in order to quantify the uncertainty of the Steel shear wall. The selected structure is a nine-storey Steel moment Frame of SAC project, which was rehabilitated by Steel shear wall. The studied structures were analyzed pre-and postrehabilitation, with probabilistic variables considered for Steel shear wall by OpenSees software. Based on results of incremental dynamic analysis and obtained fragility curves, the values of the reliability index have been obtained for the rehabilitated structure in the presence of uncertainties. Results showed that considering of uncertainties and reducing them can reduce the existing conservatism and the cost of rehabilitation.